Colored coal and process of producing the same



Patented Aug. 28, 1934 COLORED COAL AND PROCESS or PRODUCING-THE SAME Villiam A. Holst, Jr., Bayside, N. Y., assignor to National Aniline & Chemical Company, Inc., New York, N. Y., a corporation of New York No Drawing. Application 'April 19, 1930, Serial No. 445,817

8 Claims. (Cl. 44-6) This invention relates to colored coal, coke, building stone, slate, gravel, and the like material, and moreparticularly to improvements in such colored material and in a process of producing the same.

The coloring of coal, coke, building stone, and the like, as heretofore practiced, comprises spraying the material tobe colored with an aqueous suspension of a pigment, or immersing the ma- 10 terial to be colored in an aqueous suspension of a pigment and draining the excess suspension from the material. When produced in this manner, the coal or gravel or, other material is colored by reason of. a deposit of the pigment in the crevices on the surface of the material, which deposit is subject to dislodgment by the action of the elements and the handling incident to the utilization of the material.

It has also been proposed to color gravel, slate,

g0 and similar materials for roofing compositions by coating said material with a composition containing a pigment and a silicate, and heating the coated material to fuse the composition. This process cannot be used for the coloring of such' combustible material as coal, coke and the like because of the heat treatment.

An object of the present invention is to provide a colored coal, coke, building stone, slate, gravel, and like material, having a colored de-' posit on its surface capable of resisting the dislodging action of rain and of the handling incidental to the transportation and distribution of said material.

Another object of the present invention is to provide a process for coloring coal, coke, building stone, slate, gravel and like material whereby a product is readily and economically obtained having a colored deposit on its surface capable of resisting the dislodging action of rain and of 40 the handling incidental to its utilization.

A further object of the invention is to provide a process whereby coal, coke, building stone, slate, gravel, and the like may be obtained having a deposit on its surface of a pigment and an insolu- 5 ble compound containing a soap acid residue as a binder.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others which will be exemplified in the process hereinafter disclosed, and the products which may be obtained by means of said process. The scope of the invention will be indicated the claims,

In the practice of the present invention, the objects thereof are accomplished by binding a pigment to the surface of coal, coke, building stone, slate, gravel, and like material by means of a compound which shall be referred to herein as a water-insoluble soap acid compoun which expression, it is to be understood, denotes and includes the free soap acids and their waterinsoluble metallic derivatives. The term soap acid as used herein denotes and includes the higher fatty acids (both saturated and unsaturated), rosin acids, and other acids generally nection with the coloring of coal, but it will be employed in making soaps. I have found, if coal or other similar solid materialis contacted with a pigment and a substance adapted to deposit on the coal a water insoluble soap acid compound, more particularly a pigment in a finely divided condition in the presence of a water insoluble soap acid compound, the insoluble soap acid compound serves to bind the pigment to the surface of the coal or other material, thereby forming an adherent colored coating capable of resisting the washing action of rain.

The invention will be further described in conunderstood that it is not limited thereto and may be applied to'the coloring of other carbonaceous solid fuels (such as coke, wood charcoal, briquets, etc.), building stone, gravel, slate, and like materials.

The process of the invention may be performed by contacting the coal to be colored with a mixture of a pigment and. the insoluble soap acid compound, preferably in a finely divided and dispersed condition. The mixture of pigment and a water insoluble soap acid compound may be prepared in any suitable manner, and may be contacted with the coal in any suitable manner. Thus, a pigment and a free soap acid may be suspended in water, with or without the aid of a 9 dispersing agent, as for example, by inter-mixture of the pigment, acid, and water in a suitable disintegrating mixer (such as, a colloid mill of the Plauson, China, or other type); or the pigment and/or the free soap acid or an insoluble salt thereof may be formed inthe aqueous medium by conversion of a suitable intermediate product dispersed in the aqueous medium. The conversion of the intermediate product to the free soap acid or insoluble salt thereof or pigment may take place before the suspension mixture is contacted with the coal, or during or after contact. The coal may or may not be dried before shipment; but drying, at least to a partial extent, is pre ferred.

The invention may be carried out with a wide variety of pigments, as for example, the various mineral pigments, and the pigments derived from organic compounds; such as, lakes of the acid dyes, lakes of the basic dyes, lakes of the azo dyes, etc. Of the pigments derived from organic compounds, those are preferred which are relatively fast to light and to the action of the elements; e. g., alizarine lakes, vat dyes, etc.

In carrying out the process of the invention according to one method of procedure, an aqueous suspension may be prepared of a mixture which comprises a suitable pigment (e. g., one or more of the pigments above referred to) and a soap acid compound which can be converted to the free soap acid. The soap acid compound then may be converted to the free soap acid while in suspension in the aqueous medium, as for example, by the addition of a suitable converting agent, and the resulting suspension of pigment and free soap acid may be applied to the coal.

The suspension may be prepared, for example,

by mixing water with either the pigment orthe soap acid compound, and then admixing the-other substance, or by mixing all together. Any suitable soap acid compound may be employed which is adapted to be converted-as for example, by acidification--to the freesoap acid; the alkali metalsalts of the higher fatty acids or of the rosin acids, that is, the soaps (such as, ordinary commercial soap, sodium stearate, sodium oleate, sodium palmitate, sodium abietate, rosin size, Ivory soap, etc.), are preferred, however, in view of their commercial availability," relative cheapness, and emulsifying properties. The converting agent may be any suitable substance which will liberate the soap acid from the soap acid compound employed. If the soap acid compound employed is a soap, the converting agent preferably may be a suitable acidic material; such as, a mineral acid (sulfuric acid, hydrochloric acid, phosphorous acid, etc.), an inorganic acid salt (sodium acid sulfate, acid sodium phosphate, etc.), an organic acid, etc. The natural acidic waters found in some localities also may be employed as a converting agent.

The relative proportions of pigment and aqueous suspension medium employed may vary within wide limits, depending upon the pigment used and the extent of coloring desired. A suspension of approximately 5 parts of an alizarineealuminumcalcium lake in 1000 parts of water has been found to impart sufficient coloration to coal (egg size) to give it a distinct red appearance. The proportion of soap acid compound to'pigment, and of converting agent to soap acid compound also may vary within wide limits. A'soap is preferably employed in an amount sufiicient to form a relatively stable suspension of thepigment in the water, and a preferred minimum amount of acidic material is one which is sufficient to convert all of the soap to the free soap acid.

The suspension of pigment and soap acid may be applied to the coal in any suitable manner, as

for example, by immersing, spraying, washing, etc., and is preferably employed in an amount sufficient thoroughly to wet the coal.

In carrying out the process of the invention according to a modified method of procedure, an aqueous suspension of a pigment and a soap acid compound which can be converted to the freesoap acid is first prepared, as for example, by the procedure hereinbefore described. The suspension is then applied to coal Which has been pretreated with a suitable converting agent adapted to con- The reaction 1 between the'soap contained in the suspension and the'acid contained onthe surface air and light. The intimacy with which the par- ,the tenacity with whichthe lakeis held to the vert to the free soap acid the soap acid compound employed in the suspension. The reaction between the soap acid compound and the converting agent on the surface of the coal results in the formation of the corresponding free soap acid, which binds the pigment to the coal.

The pigments, soap acid compounds, and converting agents disclosed in connection withthe procedure hereinbefore described also may be employed in performing the process of the invention in accordance with the modified procedure, and they may be employed in the same relative proportions. The coal may be pretreated with the converting agent, which is preferably employed in the form of a dilute solution, in any suitable manner, as for example, by immersing, spraying, or washing, etc.

In those localities where the natural water used in wetting down the coal is itself sufiiciently acidic or contains a sufiicient amount of calcium and magnesium salts, no further pretreatment than the 'usual wetting down of the coal is required provided that the soap acid compound employed is one which can be converted by the acid or salt content of the water to the free soap acid or an insoluble salt thereof, as for example, a soap. I

The procedures hereinbefore described may. likewise be practiced with the formation of a water-insolublesalt of a' soap acid as the binding agent in place of the free soap acid by using a solution of a suitable metallic salt, such as watersoluble salts of aluminum, lead, calcium,-,and magnesium, etc., and morespecifically aluminum sulfate, lead acetate, calcium chloride, magnesium chloride, etc. as the converting agent instead of 110 an acidicconverting agent.

As illustrative embodiments of a manner in which the invention may be carried into practice and of the products produced, the following ex-- amples are presented: the parts are by weight.

Example1.40 parts of an alizarine-aluminumcalcium lake-Alizarine Red Lake, of. Dictionary of Applied Chemistry), Thorpe, vol. IV, page 21, (1922)in the form of an aqueous paste containing 12 per cent. solids, are mixed with about 1.5 parts of Ivory soap flakes (a commercial form parts of sulfuric acid to 10,000 parts of water.

of the coalproduces the fatty acids of the soap, which bind the lake .to the surface of the coal, imparting a red color which is resistant to water,

. ticles of finely divided lake, and of soap are mixed results in the formation of the fatty acid in intimate mixture with the lake, and thereby increases coal. I EramlpZe2,40 parts of 'an ali'zarine-aluminumcalcium lake, in the form of a 12 percent. aqueous paste, are mixed with a solution'of about 1.5

' parts of Ivory soap flakes in about 500 parts of water. About 458.5 part'slof acidulated water, containing about 0.3 parts of sulfuric acid is added with agitation. The resulting suspension is sprayed onto coal, whereupon the suspended lake deposits on the surface of the coal, coloring it a bright red.

Example 3.2 parts of rosin size (sodium rosinate) in aqueous solution is substituted for the Ivory soap flakes of Example 1, and the resulting taining about 12% solids are admixed with about 1.4' parts of stearic acid and about 960 parts of water in a colloid mill such asa- Plauson mill. The resulting admixture or suspension is then sprayed onto coal, whereupon the suspended lake deposits on the surface of the coal and is bound thereto by the free fatty acid, imparting a bright red color thereto.

Example .-40 parts of an alizarine-aluminumcalcium lake in the form of an aqueous paste containing about 12% solids are admixed with a solution of about 1.5 parts-of Ivory soap flakes in about 500; parts of water. To the admixture thus 7 prepared, there may be added with agitation be said to fall therebetween.

about 460 parts of water containing about 0.3 parts of aluminum sulfate. The resulting suspension is sprayed onto coal, whereupon the suspended lake deposits on the surface thereof. Y

It will be realized that the invention is not limited to the specific examples given above, but may be varied within wide limits without departing from the spirit and scope of the claims.

Thus, the pigment employed may be any other suitable pigment, such as those hereinbefore de scribed; other soap acid compounds and other converting agents may be employed; and the amounts of pigment, soap acid compound and converting agent may be varied, as has been indicated. The suspension may be applied to the coal in any other suitable manner; and instead of coal, other material may be colored in accordance with the invention, as has been before noted. The amount of suspension used relative to the .coal or other material will depend upon the ex-" ing sense.

It is also to'be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the inventionwhich, as a matter of language, might I claim:

1. In the coloring of coal, coke, building stone, gravel, slate, and like material bydepositing a pigment on the surface of the material to be .colored, the improvement which comprises formsoap acid.

gravel, slate, and like material by depositing a ing an aqueous suspension comprising a pigment and a compoundof a soap acid which can be converted to the free soap acid, and converting said compound to the free soap acid.

2. In the coloring of coal, coke, building stone, gravel, slate, and like material'by depositing a. pigment on the surface of the'material to be colored, the improvement which comprises form- I ing an aqueous suspension of a pigment and a soap, and acidifying the soap to form the free 3. In the coloring of coal, coke, building stone, gravel, slate, and like material by depositing a pigment on the surface of the material to be colored, the improvement which comprises forming a suspension of a pigment in an aqueous solution of rosin size and acidifying said rosin size to form the free rosin acids thereof.

4. In the coloring of coal, coke, building stone,

pigment on the surface of the material to be colored, the improvementwhich comprises forming an aqueous suspension comprising apigment and a compound of a soap acid which can be con- I verted to the free soap acid, and converting said 106) compound to the free soap acid by means .of a converting agent on the surface of said material, said converting agent being capable of liberating the soap acid from said compound.

5. In the coloring of coal, coke, building stone, gravel, slate, and like material, by depositing a pigment on the surface of the material to -be colored, the improvement which comprises forming an aqueous suspension of a pigment and a soap, and acidifying the soap to form the free soap acid by means of an acidic substance on the surface of said material. I

6. In the coloring of coal by depositing'a pigment on the surface thereof, the improvement which comprises forming an aqueous suspension of a'pigment and a soap, and acidifying the soap to form the free soap acid thereof by means of a lllli mineral acid contained on the surface of said coal. I

7. Theprocess of coloring coal by depositing 1 a pigment on the surface thereof which comprises agitating a pigment comprising an alizarinealuminum-calcium lake, with an aqueous solution of rosin size to form a relatively stable aqueous suspension of said pigment, applying a dilute aqueous solution of a mineral acid to the surface of the coal, and then applying said suspension to said acidified coal.

8. The process of coloring coal which comprises agitating 40 parts of a 12% paste of an alizarine aluminum-calcium lake, with about 1.5 parts of soap and about 960 parts of water and spraying the suspension so prepared on the coal which has been moistened with water containing three parts in 10,000 of sulfuric acid. I 

